In recent years, photovoltaic power generation devices have been installed in buildings, various facilities, houses, and the like from the perspective of effective utilization of natural energy. Photovoltaic power generation devices are broadly classified into a non-concentration type in which sunlight is radiated directly to photovoltaic cells and a concentration type in which sunlight concentrated by light-concentrating means such as lenses is radiated to photovoltaic cells.
Specifically, a non-concentration-type photovoltaic power generation device which is incorporated into a window structure of a building frame has been proposed (for example, see Patent Literature 1). Patent Literature 1 discloses a window structure in which an outer glass and an openable inner glass are provided in a window frame that is fitted into an opening of the frame and in which a photovoltaic battery panel is detachably attached to a window frame.
Moreover, a concentration-type power generation glass window installed in a house is proposed (for example, see Patent Literature 2). The power generation glass window disclosed in Patent Literature 2 includes a transparent substrate, a light control film provided on an incidence surface of the transparent substrate, and a photovoltaic battery disposed at an end of the transparent substrate. The light control film scatters light incident at a predetermined angle only, and a portion of the scattered light propagate inside the substrate and is received by the photovoltaic battery disposed in the end D. On the other hand, when light is incident to the light control film at a specific angle different from the predetermined angle, scattering does not occur, but incident light passes through the light control film and the transparent substrate and exits from an exiting surface.